Representative continental flood basalts (also known as traps) and oceanic plateaus, together forming a listing of large igneous provinces:[1]
We have obtained 40Ar/39Ar isochron ages using incremental heating techniques on groundmass separates, phenocryst-poor whole rock samples, or plagioclase, from eight basaltic to andesitic lavas that erupted during the Matuyama-Brunhes (M-B) polarity transition at four geographically dispersed sites. These eight lavas range from 784.6 ± 7.1 ka to 770.8 ± 5.2 ka (1 σ errors); the weighted mean, 778.7 ± 1.9 ka, gives a high-precision age that is remarkably consistent with revised astronomical age estimates for the M-B polarity transition